With regard to specific buildings having a site area of 3000 m2 or larger, such as commercial facilities and offices, the Act on Maintenance of Sanitation in Buildings, generally known as the Building Sanitation Law, stipulates an indoor temperature of 17 to 28 degrees C. and a relative humidity of 40 to 70% as control standard values for the air environment. With air conditioners becoming widespread, the indoor temperature is relatively easily controlled. However, the relative humidity is not sufficiently controlled, and especially insufficient humidification in winter needs to be addressed.
Conventional indoor humidification methods include a vaporizing method, a steaming method, and a water spraying method. In the vaporizing method, by passing air through a filter having a water absorbing property, heat is exchanged between the flowing air and water contained in the filter. Thus, the water is evaporated from the filter, and an indoor space is humidified. In the steaming method, in order to humidify an indoor space, water stored in a water tank is evaporated by energizing a heating unit for heating the water. In the water spraying method, in order to humidify an indoor space, water is micronized by applying pressure, and heat is exchanged between the micronized water and flowing air.
In a humidifier using the conventional vaporizing humidification method, a diffusing member for infiltrating water into a humidifying member, which retains the infiltrated water, is provided above the humidifying member, has a wave-shaped side, and is made of resin fibers (See Patent Literature 1, for example). In this humidifier, the wave-shaped side of the diffusing member makes it easy for water supplied from a water supply portion and diffused in the diffusing member to drop from each wave trough on the wave-shaped side, and for the water to evenly infiltrate into the humidifying member.